PRESENTATION ON

A Comparative Study of

Static and Response Spectrum Analysis

of a RC Building

PRESENTED BYTAMEEM SAMDANEE 10.01.03.127

JOHINUL ALAM 10.01.03.036

MD. ZAHIDUL ISLAM 10.01.03.142

ABU SYED MD. TARIN 10.01.03.020

UNDER THE SUPERVISION OF ZASIAH TAFHEEM

ASSISTANT PROFESSORDEPARTMENT OF CIVIL ENGINEERING,

AUST

To determine the natural period of vibrations for different mode shapes of the comprehensive 3D using modal analysis techniques.

To determine the storey-displacements and storey-drifts for each storey of a six storied building.

To determine the base shears of the building under seismic loading.

To determine the column shear forces and bending moments following the Equivalent Static Force Method (BNBC’93) and Response Spectrum Analysis (Dynamic) using a comprehensive 3D finite element software package ETABS v13.0

To make a comparative study of the results obtained from the static and dynamic analysis.

Objectives

Methodology

In this study, a 3D symmetric model of a six-storied building has been created using ETABS V-13.0

The structure has a constant stiffness and a linear behavior of all material properties.

Equivalent Static Force Method (BNBC’93) has been used for static analysis.

Response Spectrum Method has been used for dynamic analysis.

Earthquake

Earthquake is a series of vibrations induced in the earth’s crust by the abrupt rupture and rebound of rocks in which elastic strain has been slowly accumulating.

The release of the energy results in vibratory waves propagating through the surface in all directions.

Factors affecting the earthquake performance of reinforced concrete structure:

Earthquake

Ductility Capacity Effects of Drifts P-Delta effect Effects of strong Beams and weak

Columns

Static Analysis

Response Spectrum Analysis

Time History Method

Earthquake Analysis Techniques

Earthquake Analysis Techniques

Static Analysis It assumes that the building responds

in its fundamental mode.

The building must be low-rise and must not twist significantly when the ground moves.

Generally determines the shear acting due to an earthquake as equivalent static base shear.

Earthquake Analysis Techniques

Response Spectrum Analysis

The basic mode superposition method.

Restricted to linearly elastic analysis.

Produces the complete time history response of joint displacements and member forces.

Involves the calculation of only the maximum values of the displacements and member forces.

Earthquake Analysis Techniques

Time History Method

It is an analysis of the dynamic response of the structure at each increment of time, when its base is subjected to a specific ground motion time history.

Material PropertiesMaterial Name Parameter Values Unit

Concrete

Mass per unit volume 4.662 lb-s2/ft4

Weight per unit

volume

150 lb/ft3

Modulus of Elasticity 3604996.

5

psi

Poisson’s ratio 0.2  

Concrete

compressive

strength,

3500 psi

Steel Steel yield strength, 60000 psi

Section ID Section Size (in×in)

Corner Column 12×12

Ext. Column 14×14

Int. Column 17×17

Beam 16×12

Grade Beam, GB 16×12

Section Properties

Slab PropertiesSection name Thickness Type

SlabMembrane: 5"

Bending: 5"Shell

3D View of the building

Beam Layout

Column Layout

Deformed Shape (Static)

Due to EQX Load

Deformed Shape (Dynamic)

Due to Response Spectrum

Mode Name Time Period FrequenciesMode 1 2.436 0.41

Mode 2 2.34 0.42

Mode 3 2.29 0.43

Mode 4 0.704 1.42

Mode 5 0.679 1.47

Mode 6 0.657 1.52

Mode 7 0.374 2.67

Mode 8 0.359 2.78

Mode 9 0.351 2.84

Mode 10 0.245 4.08

Mode 11 0.233 4.29

Mode 12 0.231 4.32

Mode Shapes

Mode Shapes

Mode- 1 Mode- 2

Mode Shapes

Mode- 3 Mode- 4

Mode Shapes

Mode- 5 Mode- 6

Mode Shapes

Mode- 7 Mode- 8

Mode Shapes

Mode- 9 Mode- 10

Mode Shapes

Mode- 11 Mode- 12

Comparative StudyStorey Displacements

Comparative StudyStorey Drifts

Comparative StudyMaximum Storey Displacement

Comparative StudyBase Shears

Comparative StudyShear Forces (Corner Columns)

Comparative StudyShear Forces (Exterior Columns)

Comparative StudyShear Forces (Interior Columns)

Comparative StudyMaximum Shear Forces

Comparative StudyTotal Shear Forces

Comparative StudyBending Moments (Corner Columns)

Comparative StudyBending Moments (Exterior Columns)

Comparative StudyBending Moments (Interior Columns)

Comparative StudyMaximum Column Bending Moments

• In the study of Maximum displacement of storey comparison between static and dynamic, we find dynamic is 276 percent of static analysis.

• In the study of Storey drift comparison between static and dynamic, we find dynamic is 301 percent of static analysis.

• In the study of Maximum Bending moment of column, the percentage of dynamic is 204% for corner, 239% for exterior, 210% for interior of Static analysis.

• In the study of Maximum shear forces of columns, dynamic is almost 286 percent of static analysis for all columns.

Conclusion

Dynamic analysis may be done by other methods.

Structures of nonlinear materials may be introduced for further analysis and design.

Irregular shaped structure may be introduced for further analysis and design.

Dynamic analysis may be introduced for further analysis and design.

Commercial buildings may be introduced for further analysis and design.

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THANK YOU